Police were foiling two out of every three IRA terror operations by the end of the Troubles, a leading academic has revealed.

The remarkable claim by an ex-RUC Special Branch officer has been published in the latest book by Professor Richard English, called Does Terrorism Work?.

The ex-Queen’s University academic investigated the violent campaigns of the Provisional IRA, ETA, al-Qaida and Hamas and asks whether their policy of murder and mayhem achieved their goals.

Failed

Prof English argues that while the IRA were able to bomb their way into government, their overall objective of bringing about a united Ireland through violence ultimately failed.

This was due in part to the massive state intelligence operation which ended up with the IRA becoming riddled with informers.

In an interview with the Belfast-born academic, the former RUC Special Branch officer said that by the 1990s the IRA was so heavily infiltrated the majority of attacks were being foiled.

The officer claimed that two out of every three of the IRA’s planned operations were being thwarted by the state thanks to prior intelligence.

He told Prof English: “They were being contained...it became a stalemate.”

The academic states that the IRA campaign ended unionist domination of Northern Ireland and helped create the powerful political force that Sinn Fein is today.

But they failed to stop violence against Catholics and that their murder of Protestant civilians motivated some loyalists to kill in revenge.

Prof English cites the example of UVF and LVF killer Billy Wright who claimed the murder of 10 Protestant workmen by the IRA at Kingsmills in 1976 drove him to carry out sectarian killings.

“I think it’s hard to find a simple answer as regards to the Provos,” Prof English told Sunday Life.

“It’s clear that in terms of their headline objectives they didn’t succeed but I think it would be to simplistic to say that because of that they achieved nothing through violence.

“In terms of tactical and operational success and in terms of publicity and power within their own communities the violence achieved quite a lot for them.

Difficult

“The paradox of it is that in order for the violence to stop a deal had to be done with the people that were carrying out the violence.”

He continued: “The title of the book involves a rather difficult question and one that many would rather not ask.

“Some people feel that it [violence] works too much and others will feel that it hasn’t achieved as much as they would like it to have done. What I wanted to do was ask the question calmly and systematically and try to produce an historical answer.”

Does Terrorism Work? A History is published by the Oxford University Press, £25.